• 1.3 baseline — 0.6 × season 1.4 (5 gm) + 0.4 × last 10 1.2
• +0.2 opponent leak — they concede 64.3/game vs a 56.6 league average
• +0.3 at this ground — averages 1.6 there (17 gm)
• vs them: averages 2.0 over 1 game — evidence, never summed

Derived, not measured — plain arithmetic over his real games, shown in full. Adjustments can overlap (a game at this ground can also be a wet one); they add simply, and this note is the admission.